Python Panel Render 1 of 4 scenes?
This question,in relation to setting operator properties in a draw method,  is a duplicate, but can never find it.

Here is a sample draw method that adds a button to render the layer "RenderLayer" of all scenes in blend.

def draw(self, context):
    layout = self.layout
    for scene in bpy.data.scenes:
        op = layout.operator("render.render", text=scene.name)
        op.layer = "RenderLayer"
        op.scene = scene.name